Apparatus for electrolysis of the salts of alkali metals.



No. 678,851. I Patented July 23, I90].

' H. S. ANDERSON.

APPARATUS FOR ELEGTROLYSIS OF THE SALTS 0F ALKALI METALS.

(Application filed Nov. 28, 1899.)

(No Model.)

UNITED STATES PATENT OFFICE.

HENRY S. ANDERSON, OF SPRINGFIELD, MASSACHUSETTS.

APPARATUS FOR ELECTROLYSIS OF THE SALTS OF ALKALI METALS.

SPECIFICATION forming part of Letters Patent No. 678,851, dated July 23, 1901.

Application filed November 28, 1899. Serial No- 738,593. (No model.)

To all whom it may concern:

Be it known that I, HENRY S. ANDERSON, of Springfield, Hampden county, Massachusetts, have invented new and useful Imp rovements' in Apparatus for Electrolysis of Solutions of the Salts of the Alkali Metals in which Mercury is Used as a Cathode, of which the following is a specification, reference being had to the accompanying drawings and letters of reference marked thereon.

In the electrolysis of aqueous solutions of the salts of the alkali metals in the presence of a mercury cathode great trouble is experienced by the contained alkali metal of the amalgam formed decomposing the Water of the solution undergoing electrolysis, resulting in the formation of hydrates and hypochlorites, which impair the efficiency of the apparatus or cause the stoppage of the operation altogether. If the mercury cathode is kept flowing over an uneven surface which will not amalgamate therewith, a thin film of the water of the electrolyte exists between the under surface of the mercury and the impervious bottom over which it flows. This is decomposed by the alkali metals of the amalgam contaminating the original solution, as mentioned above. I have found in practice that this decomposition is due to parts of the mercury cathode being in position beyond the influence of the electrolyzing current, where none of the electrolyzing current is present to prevent the water of the solution from oxidizing the alkali metal of the amalgam.

It has been proposed to do away with the film of the electrolyte lying under the mercury by having the mercury flow over metal surfaces with which it amalgamates. While this works very well for awhile, continuous operation finally results in the disintegration of the metalsurface and its diffusion through out the mercury, the formation of a solid amalgam, and the consequent stoppage of the operation. To overcome these difficulties in effecting the continuous electrolysis of my solutions, I interpose between the under side of the mercury cathode and the impervious bottom surface a layer of porous material not attacked by the solutions. The density of the mercury prevents its passing into and through the porous lining, but the electrolytic fluid will permeate or enter and pass slowly through the porous lining, thus bringing it into contact with the lower surface of the mercury and prevent the formation of the objectionable film below the surface of the mercury. The fluid under the action of the electric current is kept constantly in motion, this being in part attributable to the diderence in temperature imparted to the fluid by the current at difierent points. If now the porous bottom be entirely covered by the mercury and no means be provided for the fluid to reach the porous lining below the mercury, it will be seen that there will be no change in this portion of the bath. Therefore to facilitate the flow of fluid to and from the portion of the receptacle below the mercury I provide the side walls of the lining with vertical openings, which, as will readily be seen, provide conduits for the passage of the electrolytic fluid to the porous lining situate below the lower surface of the mercury, thus permitting the fluid in that portion of the lining to flow out and a new supply to flow in, so that all parts of the mercury cathode and the impervious bottom surface Will be under the protecting influence of the electrolyzing current through the pores of that material filled with the original solution, and which is kept in electrical communication with the solution above the cathode by means of channels throughout the said porous material and extending above the flowing mercury.

My invention will be readily understood by reference to the accompanying drawings, like letters of reference indicating like parts.

Figure 1 is a sectional elevation of the apparatus on the line y y of Fig. 2. Fig; 2 is a plan of the same on the line cc to of Fig. 1, the cathode and electrolyte not being shown. Fig. 3 is an end elevation in section on the line 2 z of Fig. 2.

In detail, a is a tank or box made of slate or other suitable material; I), porous lining of pipe-clay, pumice-stone, or other porous material; 0, mercury cathode; d, anodes; e, the electrolyte; fiinlet-pipe for the electrolyte g, outlet for the gas formed by the electrolysis; h, outlet for spent solution; 4 electrical connection with the cathode; j, inlet for mercury; 70, Vertical channels connecting the porous lining with the electrolyte.

In thebox a, formed of slate or other suit able material, Iplace a lining of porous material, preferably of pipe-clay, though other material may be used, covering the bottom and extending up the sides to a height above the mercury and having a ridge in the center extending above the mercury for about twothirds the length of the tank. This lining thus forms a tank in which the mercury is contained. In this lining are made channels extending up the side to a height greater than the mercury, whereby the electrolyte -is allowed to permeate the porous lining and circulate beneath the mercury. In this way all parts of the mercury are kept under the influence of the electric current and all oxidation of the amalgam is prevented, because the fluid in the porous lining below the mercury may flow out through the porous bottom portion and readily escape through the vertical openings in the side Walls and because the lining is at all points filled with the electrolytic fluid. Thus all surfaces of the mercury will be in contact with the electrolytic I fluid, and consequentlywithin the field of action of the electric current. In this device any suitable anodes may be used and also any suitable receptacle and other apparatus for performing the electrolysis. The mercury is forced into the apparatus and kept in circulation therein by means of a pump conveniently located and connected with the passage j in Fig. 1 and another similar passage in the rear of the passage j.

Having therefore described my invention, What I claim, and desire to secure by Letters Patent, is-

In an electrolytic apparatus a containing vessel having a porous lining, a mercury cathode resting upon such lining, verticallyarranged channels in the lining communicating with the vessel above the level of the mercury-cathode, an anode and means for keeping the mercury in motion by forcing it into and out of the vessel.

HENRY S. ANDERSON.

Witnesses:

S. SWEENEY, DEXTER E. TILLEY. 

